The molecular chain structure and crystalline structure of PB-ET copolyester made by con-densation polymerization are studied by means of <sup>13</sup>C nuclear magnetic resonance spectroscopy(<sup>1...The molecular chain structure and crystalline structure of PB-ET copolyester made by con-densation polymerization are studied by means of <sup>13</sup>C nuclear magnetic resonance spectroscopy(<sup>13</sup>C NMR),dynamic mechanical analysis （DMA）,wide angle X-ray scattering （WAXS）,depolarized light intensity （DLI） and stress-strain measurement（S-S）.It is shown that PB-ETcopolyester is a random copolymer.Because of different ratios of EG（ethylene glycol）to BD（butane diol）in the copolyester,its crystalline forms and mechanical properties vary remarkably.With the increasing amount of BD,its crystallization kinetic parameters n,k and t<sub>1/2</sub><sup>-1</sup> increaserapidly.When EG/BD equals 25/75 （mole ratio）,the copolyester has αβ transition as PBTdoes.展开更多
Transmissible spongiform encephalopathy or prion disease is triggered by the conversion from cellular prion protein to pathogenic prion protein. Growing evidence has concentrated on prion protein configuration changes...Transmissible spongiform encephalopathy or prion disease is triggered by the conversion from cellular prion protein to pathogenic prion protein. Growing evidence has concentrated on prion protein configuration changes and their correlation with prion disease transmissibility and patho- genicity. In vivo and in vitro studies have shown that several cytosolic forms of prion protein with specific topological structure can destroy intracellular stability and contribute to prion protein pathogenicity. In this study, the latest molecular chaperone system associated with endoplasmic re- ticulum-associated protein degradation, the endoplasmic reticulum resident protein quality-control system and the ubiquitination proteasome system, is outlined. The molecular chaperone system directly correlates with the prion protein degradation pathway. Understanding the molecular mechanisms will help provide a fascinating avenue for further investigations on prion disease treatment and prion protein-induced neurodegenerative diseases.展开更多
BACKGROUND: Although the hepatoma-specific band of gamma-glutamyltransferase ( GGT ) is a highly sensitive marker in diagnosis of hepatocellular carcinoma, the kine- tic expression and the early alterations of GGT in ...BACKGROUND: Although the hepatoma-specific band of gamma-glutamyltransferase ( GGT ) is a highly sensitive marker in diagnosis of hepatocellular carcinoma, the kine- tic expression and the early alterations of GGT in the deve- lopment of hepatoma remain unclear. In this study, we in- vestigated the expression and the alterations of GGT multi- ple molecular forms in hepatotumorigenesis. METHODS: The expression of GGT in a chemically in- duced hepatocarcinogenesis model was examined by giving 0. 05% of 2-fluoenylacetamide in diet for 12 weeks. The ex- pression levels of total RNA and GGT, and the changes of liver pathology, GGT multiple molecular forms and sugar- chain heterogeneity were investigated at the different stages of rat hepatoma development. RESULTS: Pathological examination and biochemical ana- lysis found that liver GGT was over-expressed and secreted into blood during canceration. Serum total GGT and liver GGT specific activities (IU/g) including soluble and mem- brane-combined GGT were significantly higher (P <0.05) in experimental groups than those in control group, respec- tively. A highly positive correlation was found between to- tal GGT activities and total RNA levels (r =0.90, P <0.05) of the liver. Both were higher six weeks later than before. Con A-non-reactive-GGT was increased consistantly dur- ing the development of rat hepatoma. GGT multiple mo- lecular forms in the liver and sera of experimental rats showed that fetal liver-type GGT bands were associated with the development of hepatoma. CONCLUSIONS: Fetal liver-type GGT in sera and the liver of rats is closely related to hepatotumorigenesis. It can be used as a sensitive enzymatic marker for the early diagnosis of liver cancer.展开更多
文摘The molecular chain structure and crystalline structure of PB-ET copolyester made by con-densation polymerization are studied by means of <sup>13</sup>C nuclear magnetic resonance spectroscopy(<sup>13</sup>C NMR),dynamic mechanical analysis （DMA）,wide angle X-ray scattering （WAXS）,depolarized light intensity （DLI） and stress-strain measurement（S-S）.It is shown that PB-ETcopolyester is a random copolymer.Because of different ratios of EG（ethylene glycol）to BD（butane diol）in the copolyester,its crystalline forms and mechanical properties vary remarkably.With the increasing amount of BD,its crystallization kinetic parameters n,k and t<sub>1/2</sub><sup>-1</sup> increaserapidly.When EG/BD equals 25/75 （mole ratio）,the copolyester has αβ transition as PBTdoes.
基金supported by the National Natural Science Foundation of China,No.31001048
文摘Transmissible spongiform encephalopathy or prion disease is triggered by the conversion from cellular prion protein to pathogenic prion protein. Growing evidence has concentrated on prion protein configuration changes and their correlation with prion disease transmissibility and patho- genicity. In vivo and in vitro studies have shown that several cytosolic forms of prion protein with specific topological structure can destroy intracellular stability and contribute to prion protein pathogenicity. In this study, the latest molecular chaperone system associated with endoplasmic re- ticulum-associated protein degradation, the endoplasmic reticulum resident protein quality-control system and the ubiquitination proteasome system, is outlined. The molecular chaperone system directly correlates with the prion protein degradation pathway. Understanding the molecular mechanisms will help provide a fascinating avenue for further investigations on prion disease treatment and prion protein-induced neurodegenerative diseases.
基金This study was supported by a grant from Key Projects of Medical Sciences Department of Health , Jiangsu Province, China ( RC2003100 ).
文摘BACKGROUND: Although the hepatoma-specific band of gamma-glutamyltransferase ( GGT ) is a highly sensitive marker in diagnosis of hepatocellular carcinoma, the kine- tic expression and the early alterations of GGT in the deve- lopment of hepatoma remain unclear. In this study, we in- vestigated the expression and the alterations of GGT multi- ple molecular forms in hepatotumorigenesis. METHODS: The expression of GGT in a chemically in- duced hepatocarcinogenesis model was examined by giving 0. 05% of 2-fluoenylacetamide in diet for 12 weeks. The ex- pression levels of total RNA and GGT, and the changes of liver pathology, GGT multiple molecular forms and sugar- chain heterogeneity were investigated at the different stages of rat hepatoma development. RESULTS: Pathological examination and biochemical ana- lysis found that liver GGT was over-expressed and secreted into blood during canceration. Serum total GGT and liver GGT specific activities (IU/g) including soluble and mem- brane-combined GGT were significantly higher (P <0.05) in experimental groups than those in control group, respec- tively. A highly positive correlation was found between to- tal GGT activities and total RNA levels (r =0.90, P <0.05) of the liver. Both were higher six weeks later than before. Con A-non-reactive-GGT was increased consistantly dur- ing the development of rat hepatoma. GGT multiple mo- lecular forms in the liver and sera of experimental rats showed that fetal liver-type GGT bands were associated with the development of hepatoma. CONCLUSIONS: Fetal liver-type GGT in sera and the liver of rats is closely related to hepatotumorigenesis. It can be used as a sensitive enzymatic marker for the early diagnosis of liver cancer.
